1. Field of the Invention
The present invention relates to a microscope, more specially relates to a dustproof microscope and an eyepiece of dustproof microscope.
2. Related Background Art
FIG. 5 is a longitudinal, cross-sectional view of a conventional eyepiece portion of microscope. This figure shows the installed state of the eyepiece on the microscope.
The eyepiece of microscope (as will be referred simply as an eyepiece) 100 is provided with two lenses 101, 102, and a holder 110 for holding these lenses 101, 102, the holder 110 being arranged to be detachably coupled with an eyepiece mounting portion 150 of the main body of microscope (not illustrated).
The two lenses 101, 102 are fixed at predetermined positions by stopper ring 121 and separation ring 122, the stopper ring 121 being in mesh with female thread 111 formed in an inside peripheral surface of holder 110. The magnification of eyepiece is determined to be a desired value by combination of these lenses or the number of lenses.
The holder 110 is composed of inserting portion 110a having an outside diameter a little smaller than an inside diameter of the eyepiece mounting portion 150 and arranged to be inserted into the eyepiece mounting portion 150 and body portion 110b having outside diameters greater than that of the eyepiece mounting portion 150 and arranged to be mounted on the top part of the eyepiece mounting portion 150.
According to the configuration as described above, the eyepiece 100 can be mounted on the eyepiece mounting portion 150 on the occasion of observation, by inserting the inserting portion 110a into the eyepiece mounting portion 150 before abutting joint 112 of the lower end face of body portion 110b comes to abut against the top surface of eyepiece mounting portion 150; and the eyepiece can be replaced by another eyepiece 100 of a different magnification.
The eyecup 130 is mounted on the holder 110 for preventing unwanted light from the outside of eyepiece 100 entering the eye during observation. This eyecup 130 is made of an elastic material such as rubber to protect an observer's face or spectacle lens.
Incidentally, the microscopes are not always used in clean environments where the temperature and humidity are maintained moderate and where there are only a very small amount of fine particles such as dust in the air.
For example, in metal part processing factories, the microscopes are used for observing states of processed surface of part. Since a large amount of cutting oil is used in such factories, fine particles of cutting oil are always floating in the air.
The fine particles attach to the surface of microscope and also intrude even into the microscope through the clearance and the coupling parts between the eyepiece mounting portion 150 and the holder 110.
The fine particles will adhere to optical members, such as the lenses inside the microscope, causing troubles, including degradation of optical performance (degraded viewing of image upon observation).
Some treatment for removing the fine particles by overhaul or the like is necessary for recovery of optical performance by overcoming the troubles, which requires costly maintenance to maintain the required optical performance.